This invention relates to a unitary splitting device having a lower portion which converges to a point and an upper portion having a pair of oppositely facing, generally planar surfaces which diverge at an included angle at least equal to, and preferably greater than, the angle of convergence of the lower portion.
Past splitting devices, such as wedges used for splitting sections of logs, generally have been constructed with a chisel-edged lower end with substantially planar, oppositely facing sides diverging on progressing upwardly from the chisel edge. More recently, a splitting device in the form of a conical-like member has been devised as described in U.S. Pat. No. 4,194,544 to Scott and Gibson. The device of the 4,194,544 patent provides ease of startup penetration, and in the preferred embodiment produces non-directional splitting and cleavage along the line of least resistance in the object. This differs from the present invention which produces more nearly directional splitting which, as tests indicate, requires less total energy input for splitting.
Another pertinent prior art device is illustrated in U.S. Pat. No. 1,380,559 to Jespersen. Jesperson, however, describes a multi-element device which requires that the user begin penetration through striking of two loosely interconnected elements. The user then must remove one of the elements, insert a third element therebetween, and further strike it with the loosely interconnected three elements. The present invention is a decided improvement, in that it is a unitary device which provides ease of startup penetration in the object to be split and produces efficient and effective final splitting without the multi-step procedure required by Jespersen.
A primary object of the present invention is to provide a novel elongate, unitary splitting device having a substantially pointed lower end for ease of initial penetration and production of a cleavage plane in the object to be split and an upper portion having generally planar, oppositely facing diverging surfaces which serve to efficiently split the object after initial cleavage has occurred.
More specifically, an object is to provide such a novel splitting device which has a substantially diamond-shaped cross section in the lower portion thereof converging to a point at the lower end. The device also has an upper portion into which the lower diamond-shaped portion merges, the upper portion having sides with more the configuration of a standard wedge with diverging, substantially planar side surfaces. Such a hybrid design has been found to produce ease of initial penetration, directional cleavage, and effective and efficient completion of splitting through the benefits of diverging planar side surfaces in the upper portion thereof.
Another and more specific object is the provision on such a novel splitting device of gripping means for inhibiting the tendency of such a device to pop out of the object being split.